Comparison of bathymetric features detected by ERS2 SAR and LANDSAT TM DATA over San Matias gulf, Argentina

Abstract

It is well known that Synthetic Aperture Radar (SAR) is capable of imaging bathymetric features by detecting changes in sea surface roughness associated with bathymetry-induced surface current modulations. The high dynamic range of LANDSAT Thematic Mapper (TM) and Enhanced TM+ (ETM+) sensors allow them to observe oceanic surfaces affected by solar specular reflection, or sun glint, without being saturated. This ability allows the imaging of sea surface roughness patterns in the sun glint affected area that are associated with surface current changes such as those produced by bathymetric features. ERS SAR and LANDSAT TM/ETM+ images obtained over the San Matías Gulf, Argentina during similar tidal current conditions are compared and the surface signature generated by the interaction of the tidal current with the bottom topography analyzed. Each type of sensor presents advantages and limitations to the observation of bottom features due to the way each one detects sea surface roughness. Still, when sun glint is present, TM/ETM+ and SAR show similar bathymetric patterns under the same tidal conditions. While both sensors provide consistent information over significant bathymetry features, increased differences in the detection is observed over weaker features.